_CP_sr_ converts a CPSTR into a double-float number. The precision of the conversion can be changed with the _CP_precision() function.
double _CP_sr_(CPSTR * string)
/* Displays "1.12" since the conversion is truncated to the precision of 2. */
CPSTR * s = _CP_mkstr("1.12345");
double r;
_CP_precision(2);
r = _CP_sr_(s);
_CP_unix_env();
printf("%g\n", r);
_CP_str_free(s);